BARCELONA, Spain — WhatsApp, the popular messaging service for smartphones acquired this week by Facebook, will soon be offering a voice service.

CEO Jan Koum said the voice service will be deployed for Android and iPhones this spring, with BlackBerry and Microsoft and Nokia phones coming later.

"We are going to introduce voice in WhatsApp in the second quarter of this year," Koum said at the Mobile World Congress in Barcelona, Spain. "I think we have the best voice product out there. We use the least amount of bandwidth."

WhatsApp currently has a voice function but only in note form. This new service will be live.